1. Field of the Invention
This invention relates generally to an apparatus for lifting, lowering, and self-propelled transit of a person having limited use of their legs.
2. Description of Related Art
Many people require assistance moving between standing and seated positions. To reduce dependence on others, numerous devices have been developed, particularly in regard to performing everyday activities.
A conventional device for the transit of partially incapacitated persons includes U.S. Pat. No. 5,785,070, entitled Dual Handle Walking and Uprisal Assist Device, to Block et al., the contents of which are incorporated herein by reference. Block et al. provides an apparatus having a first set of handles used to assist the person when in a standing position and a second set of handles provided in a position beneath the first set of handles. The second set of handles are used to push against when the user wants to rise into a standing position. However, the apparatus of Block et al. requires use of a person's own strength to achieve the standing position, and creates an awkward sitting scenario wherein the user has to lean backward, shift weight onto the second set of handles, which may be behind and beneath the user, and then bend their knees to complete the sitting motion.
Another conventional device is described in U.S. Pat. No. 6,503,176 to Kuntz, entitled Walker Device with Power Assisted Lift, the contents of which are incorporated herein by reference. Kuntz provides a device having a compressed air assembly and a support sling to lift the user from a seated position. The device of Kuntz does not require use of upper body strength to achieve a standing position. However, the device requires use of a compressed air cylinder for power, which is inconvenient to a user due to the weight, cost and impracticality of having to transport and refill compressed air tanks. An additional limitation of Kuntz and other conventional devices is that a user is lifted along a path that differs from a natural standing motion. The unnatural lift motion makes conventional device uncomfortable to use and reduces stability.
Yet another conventional device is described in U.S. Pat. No. 6,733,018 to Razon, entitled Adjustable Leg Support and Seated to Stand Up Walker, the contents of which are incorporated herein by reference. Razon provides a stand up walker for supporting the body weight in a standing position. In Razon, a pair of upper lift arms is mounted on a walker frame with a lift spring, which lifts a user. However, the lifting motion provided by the device of Razon is unnatural, inefficient, and generally painful if the point of application of lifting force is at the armpits. While being lifted from the hips using a sling, ensuring the stability of the device is a major challenge since the center of gravity of the person being lifted is usually outside the footprint of the device. Also, for gas springs to effectively operate, exertion of a user's own strength is required during the lifting phase, to ensure that the gas springs compress during the sitting phase. In addition, gas springs generally do not provide a smooth motion.
Conventional devices fail to provide a user with a stable lifting apparatus that can be repeatedly used without fatigue. Conventional devices also fail to lift a user from a link that moves along a natural path and remains uniformly oriented throughout the lifting process.
To overcome shortcomings of conventional devices, the present invention provides a six-bar lifting apparatus that lifts a person along a natural path and maintains a constant orientation, i.e. a parallel motion, of the link of the apparatus that lifts the user. The constant orientation refers to an orientation that remains uniform and unchanged in relation to a frame of the apparatus and the user. The apparatus can support the user's weight at the buttocks and the armpit region while maintaining stability throughout the entire range of motion. The user of the apparatus of the present invention can also utilize a sling thereof as a seat when used as a walker.
The present invention provides lifting/lowering assistance between seated/standing positions, and also functions as a standard walker and/or gait trainer. Conventional devices do not provide this dual functionality.